Frequency estimation of distorted signals for control and protection of power system

This paper proposes a technique for measuring and tracing power system frequency from discrete values of one phase/three phase voltage signals. Estimation of frequency is performed using combination of two methods. The algorithm is based on combination of least error square (LES) and zero crossing (ZC) methods. This technique computes system frequency in near-nominal range of 55 to 65 Hz and traces variations of frequency at most in one cycle. The proposed technique was extensively tested using simulation data and recorded voltage signals obtained from a power system. It shows the algorithm is able to estimate frequency with good resolution. Some test results are presented in the paper.